I have a similar problem. Whatever image or logo I add to the custom header, it won’t fill the space. I need to fill all of that space, or get rid of the header altogether (which I also have been unable to do).
My site is skyviewforum.com, and I’m using the Ultimate Pro theme.
We are sorry for the late response due to some unavoidable circumstances. To remove the spacing please go to Appearance > Customizer > Design Options > Custom CSS and paste the below custom CSS code.